This invention relates to breakaway couplings for hoses, and in particular, to a field repairable breakaway coupling.
When filling cars at gas stations, customers have been known to accidentally drive away with the gasoline nozzle still in the car. To prevent damage to the gasoline pump, breakaway couplings have been inserted into the hose which connects the nozzle to the gasoline pump.
Many breakaway couplings have relied on shear pins to hold the two coupling sections together One such breakaway coupling is shown in U.S. Pat. No. 4,361,165, to Flory. Regular use of this type of coupling, however, causes wear along the pin's shear line which can lead to premature failure of the pin. Such wear is caused by pulling and releasing of the hose and line shock resulting from the shutting off of the nozzle.
Breakaway couplings which rely more on tensile forces, rather then shear forces, to effect the uncoupling overcome this problem. One solution is shown in U.S. Pat. No. 4,854,338, to Grantham and U.S. Pat. No. 4,899,786, to Morris et al. Both of these utilize a frangible sleeve. To make the coupling requires that the sleeve be molded, roll formed or pressed into annular grooves on the body 2 of the coupling. Such a design requires special equipment and is thus not easily repaired in the field.
Another breakaway coupling which is uncoupled by tensile forces is shown in U.S. Pat. No. 4,501,287 to Thompson. In this coupling, a pin or stud holds a ball in a detent, and the ball and detent hold the two coupling halves together When the pin breaks due to tensile forces, the ball falls out of the detent, allowing the two halves to separate. This coupling has many parts. It is complicated and expensive to make and difficult to repair in the field.
U.S. Pat. Nos. 4,614,201 and 4,921,000, both to King et. al., show another coupling which relies on tensile stresses In these couplings, the two halves are in an abutting relationship. The coupling may thus cock or bend at the junction of the coupling halves when the frangible element breaks. This could lead to damage of one or both of the coupling halves, requiring that the coupling be replaced.